Electric motors such as stepping motors having a plurality of pole pieces. It will be understood that while the invention has particular application to electric motors, it also has application to other apparatus having similar pole piece construction such as dynamos, tachometers, generators, etc. Accordingly the term electric motor should be deemed herein to include such other apparatus. The prior art constructions have frequently used nesting cup shaped members. While this construction has been found suitable for many applications, there are inherent problems in such a construction. These problems include holding the two or more cup shaped members, which form the stator, in a precise predetermined angular and axial relationship and then connecting them by tackwelding or other joining techniques. Obviously there are tolerances on the cooperating surfaces of the two cup shaped members which form the stator. In those motor constructions which have two axially spaced multipole stator sections, the problem of tolerance build-up between the two sections is a problem particularly because of the importance of precise orientation. The assembly operation for the prior art constructions involve significant assembly time and difficulty because the various cup shaped members cannot be easily grasped and the precise geometric relationship quickly and easily established. Still another problem is that the physical bulk of the stator assembly is increased by the overlapping cup shaped members not only in the radial but the axial dimension of the stator. In some applications it is highly desirable to minimize these dimensions and the nesting cup shaped members limit accomplishment of this goal.
It is an object of the present invention to provide a novel electric motor having a stator construction which has extremely precisely positioned stator pole pieces.
It is also an object to provide such a motor which minimizes the problem of tolerance build-up between mating parts particularly with respect to the angular orientation of the pole pieces.
It is still another object of the invention to provide a stator construction which has a minimum of physical bulk.
Yet another object of the invention is to provide a motor having a stator construction which has parts which may be manufactured with a minimum of expense and more particularly which utilizes a maximum number of parts having identical geometry.
A further object is to provide a stator construction which may be assembled with a minimum amount of time and skill preferably without the necessity for special welding or other such apparatus.